Episode Six: As the time loop restarts Marty and the Doctor try to figure out how to break the cycle, destroy the robot, rescue the lost children and deal with River's sudden memory loss. TBC in Episode Seven: Return to the Future!

"Yes, we know that part," the Doctor sighed. "Where do you come from? What is your origin?"

"Origin of manufacture California, United States of America."

Marty was a little surprised. A part of him couldn't believe these things came from the same planet as him – let alone the same state. What were these things? Terminators sent back in time to take out John Connor or whatever?

"More specific. Where is the factory?"

"42 Gale Drive, Hill Valley California, 95420."

"Well… that's quite specific," River muttered.

The Doctor wanted to say that it was too specific, that it sounded like the robot was meant to lead them to this place – to a trap – but Marty cut them all off.

"Hill Valley! My Hill Valley! A robot hunting time travellers just happened to be built in the same town I was born and raised in?" Marty wasn't just simply in disbelief about the coincidence, there was something bigger nagging in Marty's mind, something he normally would have been able to piece together, but the stress of everything that had happened so far was blocking him from realizing the most obvious conclusion.

The Doctor looked troubled too. "Date of manufacture?"

"Morton Robotics founded 2015 C.E."

"C.E?" Marty narrowed his eyes. "When the hell is that?"

"It means common era," River rolled her eyes as though it were the most obvious thing in the world.

"As in 2015 A.D," the Doctor clarified.

"2015?" The year he, Jennifer and Doc Brown had all travelled too. "Wait a minute-"

"But when were you manufactured? How far back into the past were you sent? Who really built you? Don't give me some company name, I want to know the name of the man who drew your design blueprint!"

"We're wasting our time with this," River crossed her arms in annoyance. "Now we're just wasting our time."

Time, Marty shuddered. There was no way he was going through this entire loop again.

"You're right. If we're going to find answers now, we'll find them at this Morton Robotics Company," the Doctor stood up and straightened out his jacket, turning to the others.

"What should we do with the robot?"

"Nothing. It's living off backup power cells now, those will probably die in half an hour, and it doesn't have any motor function, so as far as I can tell we're safe."

"Why am I not reassured?" Marty looked at the robot uncertainly.

"We're running out of time, we need to take care of this time loop – now," River practically ordered.

Marty walked over to the children and the boy reached out for Marty, so he leaned down and picked him up. River took the little girl and with a nod from the Doctor they ran off down the cave, back towards the crack – hopefully for the last time.

The children had calmed down and didn't feel nearly as frightened as before.

"Hey Doc," Marty remembered the conversation he had had with the little boy while they had been trapped. "I'm pretty sure – somehow – Doc Brown made this time loop. Accidentally, but still…"

The Doctor nodded. "That would make sense. A time machine careening out of control could have made that crack."

"Out of control? Do you think they're all right?"

The Doctor looked grave, but kept running. "I'm sorry, but there's no way to know right now."

They returned to the rack, River looking nervously at her watch. "How much time do you need?"

"Let me worry about time," said the Time Lord, holding his hand out to River, "you worry about supplying the explosives."

River handed him her grenade. "This won't be powerful enough. It's only a concussive grenade."

"Powerful enough to kill me in a cave-in," Marty said bitterly.

The Doctor fished some gadgets and wires out of his pockets, hooking them up to the grenade and scanning them with his sonic screwdriver.

"It just needs a little… oomph."

"Need I remind everyone that explosions in caves tend to be… bad?" Marty was beginning to feel slightly frantic. He trusted the Doctor, but he didn't see how they were going to get out of this situation unscathed.

The Doctor stood up and looked at Marty, smiling down at the young teenager as he put a reassuring hand on his shoulder. "I'm going to save us – all of us."

"Well… how?" River looked at him.

"I'm going to open the crack," he held his hand up as River started protesting what a bad idea that would be, "and throw this in. The massive amount of time in there will soak up the excess blast. We won't feel a thing, except time passing by – something you feel normally."

"This sounds like the kind of thing that can really go wrong… doesn't it?" Marty looked at River uncertainly, and she only managed to nod as the Doctor reached towards the crack.

The second his finger touched it, the crack began to react, as though it were recognizing a Time Lord in its presence.

Marty felt a rush of wind suddenly coming out of the crack and had to lean forward in order not to lose his footing. The children screamed as the crack began to open, the bright white light enveloping everything around it.

There, before the gap in time, stood the Doctor. The winds of time swirled around him violently, as he fought against the stream to push the enhanced grenade into the opening. He used both hands, and when it was far enough inside, Marty saw the flick of his wrist as he pulled the pin and suddenly the white light overwhelmed him and he closed his eyes.

When he opened them he was standing in the entrance, the Doctor at his side and River standing before them, her back to them. Marty opened his mouth to groan when he felt a tiny hand reach up and grab his own.

He looked down, and the little boy smiled up at him.

"Can we go home now?"

OOO

The five of them walked up the stone steps and into the fresh air. Marty took a deep breath as he stared up at the grey sky and the two children began laughing.

"Can you find your way home from here?" Marty asked them.

"You bet!" The little boy grinned, showing off his gapped teeth.

"And maybe in the future don't follow strange people into scary caves?" The Doctor smiled as the two of them waved and began running back to their families. They would probably never really know what had happened to them today, but all that mattered was that they were safe now.

"I think this is where our paths split," River said softly.

"But," Marty looked around. "We're in the middle of nowhere. We can't just abandon you here."

"Abandon me?" River laughed. "I'm leaving the way I came, with my own ship."

"You're in danger though. Those robots are still out there and I don't think they're going to stop until they've located every last time traveller," the Doctor looked at her with concern.

"Oh don't be so melodramatic," River took a step forward and put her hand on the Doctor's face, a sadness passing through her eyes. She looked like she wanted to say something, but stopped herself and kissed the Doctor gently on the cheek. "I'll be fine, so long as I know you're out there."

She turned to Marty and smiled at him.

"And you," she purred.

"Yeah, it was nice meeting you-" She grabbed Marty face and pulled him close, kissing him right on the lips. He was too stunned to move for a second, but then his face felt warm from embarrassment and he quickly pulled away, wiping his mouth with his sleeve as River softly laughed.

"Hey, I'm spoken for," Marty mumbled.

River shot a sideways glance at the Doctor. "So am I," she grinned. "Goodbye sweetie."

The Doctor paused, looking at her sadly, finally able to say what he hadn't had a chance to when River had died. "Goodbye, River Song."

With another wide smile she turned and walked away, disappearing behind the ruins. Marty and the Doctor watched on a moment longer, as though she might turn around and decide to join them, but she was gone for good and finally they went into the TARDIS and closed he door on Machu Picchu.

The second they were alone the Doctor ran towards the consol, his familiar joviality back, but Marty remained morose, slowly walking towards the centre of the TARDIS, his eyes staring in Jennifer's direction.

"Next stop: Hill Valley! I guess I'm going to get you home a little sooner than we thought – though probably a bit later than you thought, 30 years later actually."

"Slow down Doc."

The Doctor turned around. "You heard the robot, some company is being founded in your hometown and eventually it's going to lead to a lot of problems – for both of us. We can potentially stop everything that's happened from happening before it's even happened."

Marty's head swam for a second.

"You really think that's possible?"

"Well," the Doctor shrugged with a grin. "We're only going to find out if we try."

"Then," Marty smiled in relief. "Then I wouldn't have to waste my whole life travelling with you, waiting for Jennifer to come back to me."

"Waste? Steady on."

Marty stepped up to the consol. "I'm just kidding Doc. Despite everything that's happened… I'm not entirely sorry it did happen. You undoubtedly – and terrifyingly so – make life more interesting."

To Be Continued in Episode Seven: Return to the Future

(I find I can't be quite so loose with my metaphors in this fic. This line, for example: "like a scratched record" was "like a skipping CD" when I first wrote it. While Marty might know what a CD is, it's certainly not something he would be thinking about, so I had to change it. Same thing goes with idioms, I'm always stopping to wonder if anyone would say certain words in the 80s. To say the least, I spend more time agonizing over what Marty might say, think and perceive than any other character I've ever written – and I'm including my own writing here, not just FanFiction. Anyway, here's a fun fact: I did not make up a postal code for Hill Valley, I actually did a little research and – surprise, surprise – in BttF II there actually is a code given at one point. So that's a fun little fact about an imaginary town. Well, see you tomorrow for the exciting trip back to the future!)

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